In general, a portable electronic device such as a cellular phone, a laptop computer, or a PDA is provided therein with a storage battery so that a user can use the portable electronic device while moving.
However, the portable electronic device is equipped with an additional charger to charge power into the storage battery. The charger is connected to a typical power supply to charge power into the storage battery by supplying charge current to the storage battery of the portable electronic device. Meanwhile, in order to allow the charger to supply the charge current to the storage battery of the portable electronic device, a charger body constituting the charger must be electrically connected to the storage battery of the portable electronic device. In the case of a wired charger (contact-type charger), in order to electrically connect the charger body to the storage battery of the portable electronic device, the charger body and the portable electronic device or the storage battery individually include connectors. Accordingly, the connector of the portable electronic device or the storage battery must be connected to the connector of the charger body to charge power into the storage battery of the portable electronic device.
However, in the contact-type charger having the charger body connected to the storage body or the portable electronic device through the connector, the connector protrudes to the outside, so that an outer appearance is not only deteriorated, but the connector is contaminated with external foreign matters so that connection failure occurs. In addition, the connector is occasionally shorted due to careless use of the user, so that the storage battery may be fully discharged.
In order to solve the problem, a scheme of charging the energy of the charger body into the storage body by electrically connecting the charger body to the storage battery of the portable electronic device through a wireless (non-contact) scheme has been developed.
A wireless power transmission or a wireless energy transfer refers to a technology of wirelessly transferring electric energy to desired devices. In the 1800's, an electric motor or a transformer employing the principle of electromagnetic induction has been extensively used and then a method for transmitting electrical energy by irradiating electromagnetic waves, such as radio waves or lasers, has been suggested. Actually, electrical toothbrushes or electrical razors, which are frequently used in daily life, are charged based on the principle of electromagnetic induction. Until now, wireless energy transmission schemes include a remote telecommunication technology based on resonance or a short wave radio frequency in addition to electromagnetic induction.
In the case of a short-distance wireless power transmission, which has been spotlighted in these days, a wireless power transmitter is installed in a building in such a manner that a mobile device, such as a cellular phone or a notebook computer, can be continuously charged with power when a user uses the mobile device in the building even if the mobile device is not connected to an additional power cable.
However, the wireless power transmission technology has disadvantages in that the long charging time is required, and the power transmission distance between devices subject to the charging operation is short when the induced electromotive force is used, so that the distance allowing the use of the devices during the wireless charging operation is reduced.